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Follow-ups #3741: Exchange splice_locked messages #3873

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Follow-ups #3741: Exchange splice_locked messages #3873

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ac090a4
Don't set sent_funding_txid in maybe_promote_splice_funding
jkczyz Jun 17, 2025
eeee50e
Don't inline call to FundedChannel::splice_locked
jkczyz Jun 17, 2025
5170373
rustfmt ChannelManager::internal_splice_locked
jkczyz Jun 17, 2025
22b578b
Return new funding_txo with splice_locked
jkczyz Jun 17, 2025
db69ec7
Increase CHANNEL_ANNOUNCEMENT_PROPAGATION_DELAY
jkczyz Jun 17, 2025
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167 changes: 99 additions & 68 deletions lightning/src/ln/channel.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1424,7 +1424,7 @@ pub(crate) const COINBASE_MATURITY: u32 = 100;
/// The number of blocks to wait for a channel_announcement to propagate such that payments using an
/// older SCID can still be relayed. Once the spend of the previous funding transaction has reached
/// this number of confirmations, the corresponding SCID will be forgotten.
const CHANNEL_ANNOUNCEMENT_PROPAGATION_DELAY: u32 = 12;
const CHANNEL_ANNOUNCEMENT_PROPAGATION_DELAY: u32 = 144;

struct PendingChannelMonitorUpdate {
update: ChannelMonitorUpdate,
Expand Down Expand Up @@ -2156,6 +2156,40 @@ struct PendingSplice {
received_funding_txid: Option<Txid>,
}

#[cfg(splicing)]
impl PendingSplice {
fn check_get_splice_locked<SP: Deref>(
&mut self, context: &ChannelContext<SP>, funding: &FundingScope, height: u32,
) -> Option<msgs::SpliceLocked>
where
SP::Target: SignerProvider,
{
if !context.check_funding_meets_minimum_depth(funding, height) {
return None;
}

let confirmed_funding_txid = match funding.get_funding_txid() {
Some(funding_txid) => funding_txid,
None => {
debug_assert!(false);
return None;
},
};

match self.sent_funding_txid {
Some(sent_funding_txid) if confirmed_funding_txid == sent_funding_txid => None,
_ => {
let splice_locked = msgs::SpliceLocked {
channel_id: context.channel_id(),
splice_txid: confirmed_funding_txid,
};
self.sent_funding_txid = Some(splice_locked.splice_txid);
Some(splice_locked)
},
}
}
}

/// Wrapper around a [`Transaction`] useful for caching the result of [`Transaction::compute_txid`].
struct ConfirmedTransaction<'a> {
tx: &'a Transaction,
Expand Down Expand Up @@ -5525,6 +5559,29 @@ where
self.get_initial_counterparty_commitment_signature(funding, logger)
}

fn check_funding_meets_minimum_depth(&self, funding: &FundingScope, height: u32) -> bool {
let minimum_depth = self
.minimum_depth(funding)
.expect("ChannelContext::minimum_depth should be set for FundedChannel");

// Zero-conf channels always meet the minimum depth.
if minimum_depth == 0 {
return true;
}

if funding.funding_tx_confirmation_height == 0 {
return false;
}

let funding_tx_confirmations =
height as i64 - funding.funding_tx_confirmation_height as i64 + 1;
if funding_tx_confirmations < minimum_depth as i64 {
return false;
}

return true;
}

#[rustfmt::skip]
fn check_for_funding_tx_confirmed<L: Deref>(
&mut self, funding: &mut FundingScope, block_hash: &BlockHash, height: u32,
Expand Down Expand Up @@ -9074,58 +9131,13 @@ where
}
}

#[cfg(splicing)]
fn check_get_splice_locked(
&self, pending_splice: &PendingSplice, funding: &FundingScope, height: u32,
) -> Option<msgs::SpliceLocked> {
if !self.check_funding_meets_minimum_depth(funding, height) {
return None;
}

let confirmed_funding_txid = match funding.get_funding_txid() {
Some(funding_txid) => funding_txid,
None => {
debug_assert!(false);
return None;
},
};

match pending_splice.sent_funding_txid {
Some(sent_funding_txid) if confirmed_funding_txid == sent_funding_txid => None,
_ => Some(msgs::SpliceLocked {
channel_id: self.context.channel_id(),
splice_txid: confirmed_funding_txid,
}),
}
}

fn check_funding_meets_minimum_depth(&self, funding: &FundingScope, height: u32) -> bool {
let minimum_depth = self
.context
.minimum_depth(funding)
.expect("ChannelContext::minimum_depth should be set for FundedChannel");

// Zero-conf channels always meet the minimum depth.
if minimum_depth == 0 {
return true;
}

if funding.funding_tx_confirmation_height == 0 {
return false;
}

let funding_tx_confirmations =
height as i64 - funding.funding_tx_confirmation_height as i64 + 1;
if funding_tx_confirmations < minimum_depth as i64 {
return false;
}

return true;
self.context.check_funding_meets_minimum_depth(funding, height)
}

#[cfg(splicing)]
fn maybe_promote_splice_funding<L: Deref>(
&mut self, splice_txid: Txid, confirmed_funding_index: usize, logger: &L,
&mut self, confirmed_funding_index: usize, logger: &L,
) -> bool
where
L::Target: Logger,
Expand All @@ -9134,7 +9146,13 @@ where
debug_assert!(confirmed_funding_index < self.pending_funding.len());

let pending_splice = self.pending_splice.as_mut().unwrap();
pending_splice.sent_funding_txid = Some(splice_txid);
let splice_txid = match pending_splice.sent_funding_txid {
Some(sent_funding_txid) => sent_funding_txid,
None => {
debug_assert!(false);
return false;
},
};

if pending_splice.sent_funding_txid == pending_splice.received_funding_txid {
log_info!(
Expand All @@ -9145,6 +9163,7 @@ where
);

let funding = self.pending_funding.get_mut(confirmed_funding_index).unwrap();
debug_assert_eq!(Some(splice_txid), funding.get_funding_txid());
promote_splice_funding!(self, funding);

return true;
Expand Down Expand Up @@ -9234,7 +9253,7 @@ where

#[cfg(splicing)]
if let Some(confirmed_funding_index) = confirmed_funding_index {
let pending_splice = match self.pending_splice.as_ref() {
let pending_splice = match self.pending_splice.as_mut() {
Some(pending_splice) => pending_splice,
None => {
// TODO: Move pending_funding into pending_splice
Expand All @@ -9245,7 +9264,7 @@ where
};
let funding = self.pending_funding.get(confirmed_funding_index).unwrap();

if let Some(splice_locked) = self.check_get_splice_locked(pending_splice, funding, height) {
if let Some(splice_locked) = pending_splice.check_get_splice_locked(&self.context, funding, height) {
for &(idx, tx) in txdata.iter() {
if idx > index_in_block {
self.context.check_for_funding_tx_spent(funding, tx, logger)?;
Expand All @@ -9259,12 +9278,18 @@ where
&self.context.channel_id,
);

let announcement_sigs = self
.maybe_promote_splice_funding(splice_locked.splice_txid, confirmed_funding_index, logger)
let funding_promoted =
self.maybe_promote_splice_funding(confirmed_funding_index, logger);
let funding_txo = funding_promoted.then(|| {
self.funding
.get_funding_txo()
.expect("Splice FundingScope should always have a funding_txo")
});
let announcement_sigs = funding_promoted
.then(|| self.get_announcement_sigs(node_signer, chain_hash, user_config, height, logger))
.flatten();

return Ok((Some(FundingConfirmedMessage::Splice(splice_locked)), announcement_sigs));
return Ok((Some(FundingConfirmedMessage::Splice(splice_locked, funding_txo)), announcement_sigs));
}
}

Expand Down Expand Up @@ -9417,21 +9442,27 @@ where
}
}

let pending_splice = self.pending_splice.as_ref().unwrap();
let pending_splice = self.pending_splice.as_mut().unwrap();
let funding = self.pending_funding.get(confirmed_funding_index).unwrap();
if let Some(splice_locked) = self.check_get_splice_locked(pending_splice, funding, height) {
if let Some(splice_locked) = pending_splice.check_get_splice_locked(&self.context, funding, height) {
log_info!(logger, "Sending a splice_locked to our peer for channel {}", &self.context.channel_id);

let announcement_sigs = self
.maybe_promote_splice_funding(splice_locked.splice_txid, confirmed_funding_index, logger)
let funding_promoted =
self.maybe_promote_splice_funding(confirmed_funding_index, logger);
let funding_txo = funding_promoted.then(|| {
self.funding
.get_funding_txo()
.expect("Splice FundingScope should always have a funding_txo")
});
let announcement_sigs = funding_promoted
.then(|| chain_node_signer
.and_then(|(chain_hash, node_signer, user_config)|
self.get_announcement_sigs(node_signer, chain_hash, user_config, height, logger)
)
)
.flatten();

return Ok((Some(FundingConfirmedMessage::Splice(splice_locked)), timed_out_htlcs, announcement_sigs));
return Ok((Some(FundingConfirmedMessage::Splice(splice_locked, funding_txo)), timed_out_htlcs, announcement_sigs));
}
}

Expand Down Expand Up @@ -9925,7 +9956,7 @@ where
pub fn splice_locked<NS: Deref, L: Deref>(
&mut self, msg: &msgs::SpliceLocked, node_signer: &NS, chain_hash: ChainHash,
user_config: &UserConfig, best_block: &BestBlock, logger: &L,
) -> Result<Option<msgs::AnnouncementSignatures>, ChannelError>
) -> Result<(Option<OutPoint>, Option<msgs::AnnouncementSignatures>), ChannelError>
where
NS::Target: NodeSigner,
L::Target: Logger,
Expand Down Expand Up @@ -9958,13 +9989,18 @@ where
&self.context.channel_id,
);
promote_splice_funding!(self, funding);
return Ok(self.get_announcement_sigs(
let funding_txo = self
.funding
.get_funding_txo()
.expect("Splice FundingScope should always have a funding_txo");
let announcement_sigs = self.get_announcement_sigs(
node_signer,
chain_hash,
user_config,
best_block.height,
logger,
));
);
return Ok((Some(funding_txo), announcement_sigs));
}

let err = "unknown splice funding txid";
Expand All @@ -9988,7 +10024,7 @@ where
}

pending_splice.received_funding_txid = Some(msg.splice_txid);
Ok(None)
Ok((None, None))
}

// Send stuff to our remote peers:
Expand Down Expand Up @@ -10715,11 +10751,6 @@ where
}
}

#[cfg(splicing)]
pub fn has_pending_splice(&self) -> bool {
self.pending_splice.is_some()
}

pub fn remove_legacy_scids_before_block(&mut self, height: u32) -> alloc::vec::Drain<u64> {
let end = self
.funding
Expand Down
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